Hernandez, A., O. Ares, C. Hart, D. Domínguez, H. Pastoriza, and A. Butera. "Dissipation in mesoscopic superconductors with ac magnetic fields." Journal of Low Temperature Physics 135 (2004): 119–122.
Abstract: The response of mesoscopic superconductors to an ac magnetic field is investigated both experimentally
and with numerical simulations. We study small square samples with dimensions of the order of the penetration depth.
We obtain the ac susceptibitity $\chi=\chi'+\chi"$ at microwave frequencies as a function of the dc magnetic field
$H_{dc}$. We find that the dissipation, given by $\chi"$, has a non monotonous behavior in mesoscopic samples.
In the numerical simulations we obtain that the dissipation increases before the penetration of vortices and
then it decreases abruptly after vortices have entered, the sample. This is verified experimentally, where we
find that $\chi"$ has strong oscillations as a function of $H_{dc}$ in small squares of Pb
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Tovar, M., J. G. Sereni, P. Pedrazzini, A. Caneiro, F. Prado, A. Butera, and M. T. Causa. "Magnetization and specific heat of La doped Sr2FeMoO6." JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS 272 (2004): 857–858.
Abstract: We present high-temperature magnetization and low-temperature specific heat measurements performed on the electron doped double perovskite Sr1.7La0.3FeMoO6. We have obtained the electronic contribution to C-p, gamma = 11.5(5) mJ/mol K-2. The electronic susceptibility, derived from the magnetic measurements in the paramagnetic regime (T > T-c = 390K), was chi(e)(0) =(4.9 +/- 1.5) x 10(-4) emu/mol. Anti ferromagnetic coupling between localized and itinerant moments was inferred from the data, with a coupling constant lambda = -(475 +/- 50)mol/emu, that results in a ferromagnetic-like Curie-Weiss susceptibility with Theta = 390(5) K. These results are compared with those obtained for the undoped material. (C) 2003 Published by Elsevier B.V.
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